It's been several years since the last treatment guideline updates for either of these conditions. "It was felt that there had been significant developments in both areas,” says Eamonn M.M. Quigley, MD, who co-wrote the guidelines. He is chief of gastroenterology and hepatology at Houston Methodist Hospital and Weill Cornell Medical College in Houston, Texas.

Quigley and a team of researchers reviewed the available scientific evidence for IBS and chronic constipation that is not due to a known cause (known as chronic idiopathic constipation). The guidelines were released by the American College of Gastroenterology and are published in the August issue of the American Journal of Gastroenterology.

Big Medicine Changes

Drug treatments for IBS and CC have evolved in recent years. The biggest change is the development of medicines that work directly in the digestive tract. "They do not have to be absorbed into the bloodstream to be effective in the [gastrointestinal] tract,” Quigley says.

The researchers give Amitiza (lubiprostone) and Linzess (linaclotide) a strong recommendation for both conditions.

"Both of these [drugs] seem to be effective for both chronic constipation and [IBS]," Quigley says.

Diet: What You Eat Does Matter

People with IBS have been telling their doctors for years that certain foods aggravate their symptoms. The new guidelines show they were right.

"When you stand back and look, there are a number of things that do jump out," Quigley says. "The first thing is the emergence of diet as a major issue in [IBS]. For patients, this isn't new, because patients have contended for years that certain foods upset them, but we were very dismissive of that." Now though, he says, good evidence suggests that diet is important -- probably not of the cause of [IBS], but a factor in attacks.

Though specialized diets may improve symptoms in some people with IBS, the researchers give them only a weak recommendation, since there is little solid evidence to support them.

Quigley says there's enormous interest in the gluten-free diet among people with IBS, as well as evidence it may help, but the research is controversial.

The researchers also give a nod to diets low in certain types of sugars. This diet includes avoiding foods like certain fruits (apples, pears, mangos, etc.), dried fruits, honey, and sweeteners like high-fructose corn syrup.

"There is, I think, now quite good evidence that this diet can help some people,” Quigley says.